The presently disclosed embodiments relate generally to a method for magnetic actuated milling which uses magnetic particles and magnetic field to facilitate the pigment dispersions useful in making toner suitable for electrophotographic apparatuses.
Numerous processes are within the purview of those skilled in the art for the preparation of toners. Emulsion aggregation (EA) is one such method.
The pigment dispersion is an important component in the preparation of EA toner. In order for pigment particles to form aggregates with the latex particles, the pigment particles should have size smaller or at least a size comparable to the latex particles, preferably between about 5 and 300 nanometers in diameter. Conventional mechanical impeller milling system loses its efficiency throughout the whole reaction vessel. For pigment dispersion utilizing an in-line rotor-stator type homogenizer; the length of process time exceeds four hours. It has also been generally accepted that mechanical components has main concerns on maintenance including: large consumption of solvents for cleaning; frequent pumping in/out for cleaning pumps/pipelines; anti-resonance design to layout system, floor space and flexibility. Furthermore, these systems are working on macro-scale bulk shearing and are not ideal for preparing small size particle especially in the size range of nanometer and submicron, which is a typical range of pigment particles used as an EA toner component. Therefore, micro-scale driven milling could be preferable.
There remains a need to develop a dispersion technology which reduces processing time and cost, without sacrificing benchmark material properties (e.g., small size and narrow particle size distribution).